A highly efficient chemical sensor material for H2S: α-Fe2O3 nanotubes fabricated using carbon nanotubes as templates in supercritical (SC) CO2 modified with ethanol was investigated. The as-prepared αFe2O3 nanotubes, characterized by a uniform size and shape with a high specific surface area, exhibited superior sensitivity to hydrogen sulfide based on the catalytic chemiluminescence (CL). X-ray diffraction (XRD) analysis was used to determine the chemical composition and crystal structure of the sample. The results show no detectable CL signal from 109 to 240 °C, which suggests the high selectivity of the sensor for H2S.